Determination of steep sidewall angle using polarization-sensitive asymmetric scattering

Dou, X.; Pereira, S.F.; Min, Changjun; Zhang, Yuquan; Meng, P.; Urbach, Paul; Yuan, Xiaocong

doi:10.1088/1361-6501/abfbac

Determination of steep sidewall angle using polarization-sensitive asymmetric scattering

Title

Determination of steep sidewall angle using polarization-sensitive asymmetric scattering

Author

Dou, X. (TU Delft ImPhys/Optics; Shenzhen University)
Pereira, S.F. (TU Delft ImPhys/Optics)
Min, Changjun (Shenzhen University)
Zhang, Yuquan (Shenzhen University)
Meng, P. (TU Delft ImPhys/Optics)
Urbach, Paul (TU Delft ImPhys/Optics)
Yuan, Xiaocong (Shenzhen University)

Date

2021

Abstract

The sidewall angle (SWA) of a nanostructure exerts influence on the performance of the nanostructure and plays an important role in processing nano-structural chips. It is still a great challenge to determine steep SWAs from far field measurements especially when the SWAs are close to 90°. Here, we propose a far-field detection system to determine steep SWA of a cliff-shape step structure on a silicon substrate by combining a split detector with a scanning method. The far-field radiation field is asymmetric due to the scattering of the step structure, and further numerical analysis demonstrates the reliability of this far-field measurement method. In the simulations, two key variables, i.e. the polarization state and the focus position of the incident laser beam, are considered to explore their impacts. By scanning over the structure laterally and longitudinally with both TE and TM polarizations, polarization effects on the far-field occur. These effects show higher sensitivity to steep SWA variation for TM polarization as compared to TE. Furthermore, with a comprehensive longitudinal scanning analysis for the TM polarization case, a feasible focus interval can be optimized to retrieve the steep SWA. As the proposed method is fast, highly sensitive and easy to implement, it provides a powerful approach to investigate the scattering behavior of nanostructures.

Subject

optical metrology
Optical scattering
sidewall angle retrieval

To reference this document use:

http://resolver.tudelft.nl/uuid:e545d5f9-be21-4cb6-83be-b8306bd04e10

DOI

https://doi.org/10.1088/1361-6501/abfbac

ISSN

0957-0233

Source

Measurement Science and Technology, 32 (8)

Part of collection

Institutional Repository